The subject matter described herein relates to a combustible fuel burning stove with a fire grate. This fire grate has particular but not exclusive utility for portable back yard firepits.
Portable wood burning stoves are used in camping and make use of twigs and sticks as fuel for heat and cooking. Similarly, large portable firepits are used for example in residential back yards for recreation, to provide outdoor heat, and to support limited cooking such as marshmallow roasting.
However, large firepits are generally fueled by piles of heavy logs rather than small twigs, which places significantly greater structural demands on the firepit materials. When experiencing repeated cycles of cold (during disuse) and high heat (during use), fire grates for large firepits are subject to bowing or sagging that may be aesthetically displeasing, may cause a poor fit with other components of the firepit, and may cause unwanted contact with other components of the firepit, or with the ground, thus presenting a potential fire risk. Large fire grates are also subject to oxidation, and to other deformation that may limit their service life and may, in some circumstances, cause dangerous structural failure with additional attendant fire risk. Conventional fire grates are subject to deformation or may have insufficient air flow, which in turn may lead to inadequate combustion of fuel, inadequate heat production, and excessive generation of smoke. Such heavily built structures are also heavier (and therefore less portable), they require more material to construct, and they may also require more complex (and therefore more expensive) manufacturing steps.
It is therefore to be appreciated that such commonly used fire grates have numerous drawbacks, including one or more of high cost, large weight, low portability, poor performance, short service life, smoke generation, fire risk, aesthetic degradation, among others. Accordingly, long-felt needs exist for fire grates that address the forgoing and other concerns.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosure is to be bound.
Disclosed is a fire grate for a wood burning stove. One general aspect includes a stove including: a dome-shaped fire grate including: a center; a perimeter surrounding and spaced from the center, the center being higher than the perimeter; a plurality of radial stiffening ribs extending away from the perimeter and toward the center; at least one circumferential stiffening ring extending at least partially about the center; and a plurality of ventilation holes between the center and the perimeter.
Implementations may include one or more of the following features. The stove where the perimeter is circular. The stove where the dome-shaped fire grate is a spherical section with a radius of curvature larger than one-half of a width of the fire grate. The stove where the center includes a central hub. The stove where the fire grate further includes a downward-facing lip around the perimeter. The stove where the plurality of radial stiffening ribs include ribs of at least two different lengths. The stove where a portion of the dome-shaped fire grate includes an outer stiffening ring that includes no ventilation holes. The stove where the dome-shaped fire grate, the plurality of radial stiffening ribs, the at least one circumferential stiffening ring, and the ventilation holes are arranged in a manner that they can be produced by stamping a flat blank of metallic material. The stove including: an outer wall, an inner wall spaced from the outer wall by a gap, the inner wall forming a cavity, and where the dome-shaped fire grate is disposed in the cavity. The stove where the ventilation holes are in fluid communication with the gap in a manner assisting with air flow through the gap, and where the fire grate is configured to support between 0 lb and about 190 lb of fuel at temperatures of between about −40 f and about 1350 f.
One general aspect includes a fire grate for a combustion stove, including: a domed shape having a center and a perimeter, where the center is higher than the perimeter; a plurality of radial stiffening ribs extending away from the perimeter and toward the center; at least one circumferential stiffening ring extending at least partially about the center; and a plurality of ventilation holes between the center and the perimeter.
Implementations may include one or more of the following features. The fire grate where the perimeter is circular. The fire grate where the domed shape is a spherical section with a radius of curvature larger than one-half of a width of the fire grate. The fire grate including a central hub. The fire grate including a downward-facing lip around the perimeter. The fire grate where the plurality of radial stiffening ribs extend from the perimeter, and include radial stiffening ribs of at least two different lengths. The fire grate where a portion of the domed shape includes an outer stiffening ring that includes no ventilation holes. The fire grate where the shape of the fire grate is configured to enable production by stamping a flat blank of metallic material.
One general aspect includes a stove for burning solid fuel to produce heat, including: an inner wall having a lower portion and an upper portion; an outer wall having a lower portion and an upper portion; an air-filled space between the inner and outer wall; a chimney formed by the inner wall; a combustion area situated within the chimney; at least one ventilation hole within the upper portion of the inner wall; at least one ventilation hole within the lower portion of the outer wall; a fire grate situated within the combustion area, including: a domed shape having a center and a perimeter, where the center is higher than the perimeter; a plurality of radial stiffening ribs substantially oriented toward the center; at least one circumferential stiffening rings substantially concentric with the center; a stiffening lip around the perimeter; and a plurality of ventilation holes. Implementations may include the stove where the fire grate is supported only at the perimeter.
The fire grate disclosed herein has particular, but not exclusive, utility for portable back yard firepits.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the fire grate, as defined in the claims, is provided in the following written description of various embodiments of the disclosure and illustrated in the accompanying drawings.
Illustrative embodiments of the present disclosure will be described with reference to the accompanying drawings, of which:
For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.
In accordance with at least one embodiment of the present disclosure, a fire grate for a wood burning stove is provided which includes novel structural features to prevent significant bending, bowing, sagging, or other deformation under the heat loads expected during normal use cases and plausible exceptional use cases. These features provide the necessary structural performance to support heavy fuel loads at high temperature, while permitting a relatively low weight for the fire grate itself. The disclosed fire grate also includes air flow features conducive to thorough combustion of fuel, which leads to greater heat generation and substantially reduced smoke. The design may be readily manufactured as a single piece (e.g., stamped from a sheet metal blank), which permits it to be lighter and less expensive than a multipart assembly of comparable strength.
These descriptions are provided for exemplary purposes only and should not be considered to limit the scope of the fire grate. Certain features may be added, removed, or modified without departing from the spirit of the claimed subject matter.
In the example embodiment of
The stove 150 further includes a base plate 170 attached to the outer body 120, a bracing tray 175 supported by stands projecting upward from the base plate, and a catch tray 180 supported by stands projecting upward from the bracing tray 175 such that the bracing tray is separated from the outer body by an air gap 176, the catch tray 180 is separated from the outer body 120 by an air gap 178, and the inner body is separated from the outer body by an air gap 179. In an example, air gaps 176 and 179 are both about 50 mm, while air gap 178 is about 100 mm, although other air gaps may be employed that have the disclosed, advantageous effect.
The cavity 190 is in fluid communication with the air gap 179 via the inner ventilation holes 124, and with air gaps 178 and 176 via the fire grate 100. The air gaps 176 and 178 are in fluid communication with ambient air via the outer ventilation holes 122, such that ambient air may be drawn in through the outer ventilation holes 122, heated by combustion of the fuel 160, and expelled through the cavity 190 and inner ventilation holes 124 to produce advantageous combustion of the fuel 160.
In an example, both the fire grate 100 and the stove or firepit 150 are made of stainless steel plates having a thickness within a range of between about 0.5 mm and about 2.5 mm thick. Some examples of the fire grate 100 and the stove or firepit 150 are formed of 1.0 mm to 2.0 mm thick, and one example is about 1.5 mm thick stainless steel. Both thicker and thinner materials are contemplated. In an example, the fire grate 100 weighs approximately 48 lb (21.8 kg), although weights of between about 9 oz and about 88 lb may be provided. In an example, during normal operation the fire grate 100 supports a nominal weight of 100 lb (45.4 kg), (although nominal capacities of between about 5 lb and about 190 lb may be provided), while the fire grate 100, or portions thereof, are heated to between about about 700° F. (371° C.) and about 1350° F. (732° C.) by the combustion of the fuel 160, for a time period of between 1 and 12 hours, and also at ambient temperatures as low as −40° F. (−40° C.)In an example, during normal operation over a period of years, with repeated cycling (e.g., one hundred cycles) between ambient and operational temperatures, the fire grate 100 exhibits little or no warping that would detrimentally affect its aesthetic appearance, its performance, or its fit within the stove or firepit 150.
The primary load carried by the fire grate 100 is applied downward, in a direction parallel to axis 270, by the weight of the fuel 160 piled on the fire grate 100, which is supported by the upward-facing lip or rollover 112 of the inner body 110.
In an example having an outer diameter 420 (see
In the implementation in
The fire grate 100 in the example shown in
In addition to the plurality of ventilation holes 330, the ventilated inner ring 325 includes an outer concentric stiffening ring 360 and an inner concentric stiffening ring 370 that provide additional strength, stiffness, and stability to the structure of the fire grate 100, both at ambient temperature and at operating temperatures when a fire is burning in the fire pit 150 that includes the fire grate (see
In the example shown in
In an example, the hub 320, short stiffening ribs 330, long stiffening ribs 350 and 355, stiffening rings 370 and 370 are stamped or otherwise embossed into the material of the fire grate (e.g., stainless steel), although other fabrication methods may be employed. In an example, the fire grate is a spherical section which is formed from a flat, circular blank by the stamping process. In an example, the holes 330 and 323 are also formed by the stamping process, although they may alternatively be produced by drilling, laser cutting, or other methods.
In some embodiments, one or more of the holes 330 may overlap with one or more of the stiffening ribs 340, 350, or 355, or stiffening rings 360 and 370. However, in other embodiments the hole pattern, rib pattern, and ring pattern have been selected such that no holes 330 overlap with any of the ribs 340, 350, or 355, or rings 360 and 370.
The fire grate 100 also includes the plurality of short radial stiffening ribs 340, each separated from its nearest neighboring short radial stiffening rib 340 by an angle 470. The fire grate 100 includes a plurality of long radial stiffening ribs 355 interleaved with slightly longer radial stiffening ribs 350. Each long radial stiffening rib 350 or 355 is separated from its nearest neighboring long radial stiffening rib 350 or 355 by an angle 450, and from its nearest neighboring short radial stiffening rib by an angle 460. In an example, angle 450 is 30 degrees, while angles 460 and 470 are both 10 degrees. However, other angle spacing is contemplated.
The length of the short radial ribs 340 is roughly equal to one half the difference between diameter 410 and diameter 420. In an example, this number is equal to 60 mm, and the short radial ribs 340 are each about five millimeters longer than that, although other lengths may be employed. In an example, the length of the long radial stiffening ribs 350 is about 322.5 mm, and the length of the long radial stiffening ribs 355 is about 317.5 mm, although other lengths could be employed.
The fire grate 100 is made strong and stiff for load bearing of firewood and other fuel, both at ambient temperatures and at operating temperatures, by a balanced combination of a domed shape, a vertically folded outer lip 312, stiff outer ring 315, short radial stiffening ribs 340, long radial stiffening ribs 350 and 355, a central hub, and stiffening rings 360 and 370. At the same time, the fire grate 100 is ventilated by a ventilated inner ring 325 that includes a plurality of ventilation holes 330, and by a single ventilation hole 323 at the center of the central hub 320. The ventilation provided by these features is sufficient to provide high air circulation through the stove or firepit 150 to yield a high heat output and low smoke output relative to existing stoves and firepits.
Accordingly, it can be seen that the fire grate 100 fills a long-standing need in the art, by providing a low-cost, lightweight, stampable, high-strength, high-stiffness, high-airflow structure that resists denting, warping, and other deformation while carrying heavy fuel loads at operating temperatures as high as about 1350° F. (732° C.), and while cycling repeatedly between ambient temperature and operating temperature.
A number of variations are possible on the examples and embodiments described hereinabove. For example, the fire grate could be made of heavier-gauge material in order to support more weight, or of lighter gauge material in order to become lighter and more portable. The fire grate could be made in different sizes and/or with different degrees of curvature. The relative lengths, widths, and radii of different components could be different than presented herein. The fire grate could be made by different processes, including casting, forging, sintering, milling, or 3D printing. It could be made of different metals, or of nonmetallic materials such as ceramics. The outer rim could be noncircular, including such possible shapes as ovals, rectangles, triangles, and rhombuses. The technology described herein may be used to burn firewood, wood chips or pellets, scrap lumber, paper, cardboard, coal, and other combustible materials. It may be employed for example in lamps, stoves, firepits, fireplaces, furnaces, forges, and boilers, and other combustion heaters. In some implementations, more than one fire grate may be used, or the fire grate may comprise several pieces that collectively form a structure like that described herein.
The logical operations making up the embodiments of the technology described herein are referred to variously as operations, steps, objects, elements, components, or modules. Furthermore, it should be understood that these may be performed in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.
All directional references e.g., upper, lower, inner, outer, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, proximal, and distal are only used for identification purposes to aid the reader's understanding of the claimed subject matter, and do not create limitations, particularly as to the position, orientation, or use of the fire grate. Connection references, e.g., attached, coupled, connected, and joined are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other. The term “or” shall be interpreted to mean “and/or” rather than “exclusive or.” Unless otherwise noted in the claims, stated values shall be interpreted as illustrative only and shall not be taken to be limiting.
The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the fire grate as defined in the claims. Although various embodiments of the claimed subject matter have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the claimed subject matter. Still other embodiments are contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the subject matter as defined in the following claims.
This application is a continuation of co-pending U.S. patent application Ser. No. 16/366,799 filed Mar. 27, 2019, entitled “Combustible Fuel Burning Stove with Fire Grate,” which is hereby incorporated by reference in its entirety for all purposes.
Number | Name | Date | Kind |
---|---|---|---|
685194 | Young | Oct 1901 | A |
904188 | Engle | Nov 1908 | A |
1298762 | Milligan | Apr 1919 | A |
D54930 | Knapp | Apr 1920 | S |
D74996 | Wolcott | Feb 1928 | S |
1694175 | Hauser | Dec 1928 | A |
D100012 | Ford | Jun 1936 | S |
2722883 | Rignell | Nov 1955 | A |
2738225 | Meek | Mar 1956 | A |
D196018 | Palmer et al. | Aug 1963 | S |
3756218 | Simpson | Sep 1973 | A |
D229013 | Storandt | Nov 1973 | S |
D229277 | Chan | Nov 1973 | S |
3790081 | Thornton | Feb 1974 | A |
3937138 | Tidwell | Feb 1976 | A |
3951082 | Leggett | Apr 1976 | A |
D258259 | Lindholm | Feb 1981 | S |
D258712 | Jacobson | Mar 1981 | S |
D273264 | Elliston | Apr 1984 | S |
4735135 | Walker | Apr 1988 | A |
4903683 | Larsen | Feb 1990 | A |
5024208 | Hottenroth et al. | Jun 1991 | A |
5117558 | Hull | Jun 1992 | A |
D355809 | Kothrade | Feb 1995 | S |
D358204 | Ferrier | May 1995 | S |
D379900 | Gillam | Jun 1997 | S |
5638808 | Home | Jun 1997 | A |
5651356 | Kaines | Jul 1997 | A |
5797386 | Orr | Aug 1998 | A |
6024081 | Libertini | Feb 2000 | A |
D422452 | Persson | Apr 2000 | S |
D435191 | Cooper | Dec 2000 | S |
6196121 | Crowl | Mar 2001 | B1 |
6196215 | Chandaria | Mar 2001 | B1 |
D442422 | Dabney | May 2001 | S |
D444991 | Measom | Jul 2001 | S |
6314955 | Boetcker | Nov 2001 | B1 |
6393717 | Santos | May 2002 | B1 |
6488023 | Pecoskie | Dec 2002 | B2 |
6598598 | Bratsikas | Jul 2003 | B1 |
D488023 | Siegel et al. | Apr 2004 | S |
D491409 | Siegel et al. | Jun 2004 | S |
D495552 | Siegel et al. | Sep 2004 | S |
D531849 | Turner | Nov 2006 | S |
D534756 | Jensen | Jan 2007 | S |
D607265 | Gaunaurd, III | Jan 2010 | S |
D612191 | Taber et al. | Mar 2010 | S |
D612662 | Lorenz et al. | Mar 2010 | S |
D618038 | Davies et al. | Jun 2010 | S |
7810484 | Schlosser | Oct 2010 | B2 |
D644474 | Wilgus et al. | Sep 2011 | S |
8087410 | Gregory | Jan 2012 | B2 |
D658426 | Saunders | May 2012 | S |
D683999 | Karlsson | Jun 2013 | S |
D701721 | Jan | Apr 2014 | S |
9844300 | Cedar | Dec 2017 | B2 |
10098502 | Ohler | Oct 2018 | B2 |
10125995 | Kohli | Nov 2018 | B2 |
10222092 | Traeger | Mar 2019 | B1 |
D858729 | Scott | Sep 2019 | S |
11199324 | Jan | Dec 2021 | B2 |
11391465 | Weilert | Jul 2022 | B1 |
11879641 | Weilert | Jan 2024 | B2 |
20060219233 | Sorenson | Oct 2006 | A1 |
20090165772 | Hunt | Jul 2009 | A1 |
20100043775 | Phillips | Feb 2010 | A1 |
20110180527 | Abbott | Jul 2011 | A1 |
20140026765 | Fou | Jan 2014 | A1 |
20140238378 | Scott | Aug 2014 | A1 |
20150068512 | Mehler et al. | Mar 2015 | A1 |
20150110939 | Benson et al. | Apr 2015 | A1 |
20150211743 | DeFoort et al. | Jul 2015 | A1 |
20170363325 | Diurlin et al. | Dec 2017 | A1 |
20180187896 | Aguilar et al. | Jul 2018 | A1 |
20210018180 | Jan | Jan 2021 | A1 |
Number | Date | Country |
---|---|---|
2035756 | Apr 1989 | CN |
201108346 | Sep 2008 | CN |
201748447 | Feb 2011 | CN |
102015221099 | Apr 2017 | DE |
2146762 | Apr 1985 | GB |
2000-342462 | Dec 2000 | JP |
20-0295935 | Nov 2002 | KR |
100818931 | Apr 2008 | KR |
10-0898493 | May 2009 | KR |
100898493 | May 2009 | KR |
162985 | Jul 2016 | RU |
Entry |
---|
Old Smokey: Old Smokey Products Company—Bottom Grate, Dec. 23, 2015, XP055970754, Retrieved from the Internet : URL :https : //web . archive . org/web/2015122309 5511/http : //www . oldsmokey.com/products/add on-grates-grills?variant=4 12 981533 [retrieved on Oct. 13, 2022], 1 page. |
The Hague, Extended European Search Report and Search Opinion for European Patent Application No. 19922139.1, dated Oct. 25, 2022, 10 pages. |
International Search Authority, International Search Report and Written Opinion, ISA/KR, PCT/US2019/063180, Mar. 26, 2020, 10 pages. |
China National Intellectual Property Administration, Office Action for Chinese patent application No. 201980094763.8, dated Dec. 27, 2023, 10 pages. |
Number | Date | Country | |
---|---|---|---|
20220074590 A1 | Mar 2022 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 16366799 | Mar 2019 | US |
Child | 17526598 | US |